
class MulLayer:
    def __init__(self):
        self.x = None 
        self.y = None 

    def forward(self,x,y):
        self.x = x
        self.y = y
        out = x*y 
        return out 
    
    def backward(self,dout):
        dx = dout*self.y
        dy = dout*self.x

        return dx,dy
    
class AddLayer:
    def __init__(self):
        pass
    def forward(self,x,y):
        out = x + y 
        return out 
    def backward(self,dout):
        dx = dout * 1
        dy = dout * 1
        return dx,dy 
        